Atlas V has an extraordinary reliable launch record. Why wasn't it upgraded to become certified for human spaceflight, especially when it was decided to cancel the STS space shuttle? It is capable to carry the CST-100 Starliner, so it is obviously intended to become human rated anyway now.

Why was Orion developed for a potential future much heavier launcher instead of for the already existing and proven Atlas V?

The infamous ESAS study of 2005 (the one that recommended the 1.5-launch architecture for Constellation) claimed that EELVs were unsafe for crew launch, because their lofted trajectories meant crews would face unacceptably high G-loads during an abort in certain phases of flight ("black zones").

Eventually the black-zone myth was debunked (see the attachment).

It's hard not to suspect that ESAS's erroneous support for the existence of EELV black zones may have been motivated at some level, possibly subconscious, to justify Ares I.

The infamous ESAS study of 2005 (the one that recommended the 1.5-launch architecture for Constellation) claimed that EELVs were unsafe for crew launch, because their lofted trajectories meant crews would face unacceptably high G-loads during an abort in certain phases of flight ("black zones").

Eventually the black-zone myth was debunked (see the attachment).

It's hard not to suspect that ESAS's erroneous support for the existence of EELV black zones may have been motivated at some level, possibly subconscious, to justify Ares I.

Atlas 5 could not lift a 25 tonne Orion, and still can't. That's why. (To date, the heaviest known Atlas 5 payload has only weighed a bit less than 7.5 tonnes.)

Heavy would have been required. The lofted-trajectory "black zones" were only with single-engine Centaurs. Two-engine Centaur or a new upper stage with more thrust would have been needed.

Notice how the Starliner launch vehicle will use two RL-10s?

Also, when discussing the OP topic, keep in mind that when Shuttle was cancelled in January 2004 Atlas 5 had only flown three times.

The infamous ESAS study of 2005 (the one that recommended the 1.5-launch architecture for Constellation) claimed that EELVs were unsafe for crew launch, because their lofted trajectories meant crews would face unacceptably high G-loads during an abort in certain phases of flight ("black zones").

Eventually the black-zone myth was debunked (see the attachment).

It's hard not to suspect that ESAS's erroneous support for the existence of EELV black zones may have been motivated at some level, possibly subconscious, to justify Ares I.

Atlas 5 could not lift a 25 tonne Orion, and still can't. That's why.

- Ed Kyle

The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. Because of the delay time in solids destruction, it makes it very difficult to achieve the 1:1000 LOC. Atlas has RD-180s. DOD did not want to alter its configuration for HSF. The major reason, was with propellant transfer and long term storage, you do not need HLV shuttle derived.

Any proposal to innovate in the LV industry fell on deaf ears for decades. Ever wonder why it was called 'Delta'?

Atlas V has an extraordinary reliable launch record. Why wasn't it upgraded to become certified for human spaceflight, especially when it was decided to cancel the STS space shuttle? It is capable to carry the CST-100 Starliner, so it is obviously intended to become human rated anyway now.

While ULA has said both Atlas V and Delta IV Heavy can safely launch humans to space (ULA paper - date unknown), when the end of the Shuttle program was coming near the end and Ares I was having development challenges, ULA proposed Delta IV Heavy to be human rated. At the time (and I can't find the slide at this moment), ULA said it would be something like $1.4B to human rate and only take a couple of years.

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Why was Orion developed for a potential future much heavier launcher instead of for the already existing and proven Atlas V?

I think Michael Griffin, the NASA Administrator at that point in history, is responsible for that decision. I think it was a bad one, but no need to debate it now...

I was a NASA engineer in the middle of all this at the time it happened. Atlas trajectories had no black zones from the start. The existing Delta trajectories had black zones. I requested we ask ULA/Boeing to lower the Delta trajectories but NASA management refused to ask ULA/Boeing to do this, even though the current trajectories made the Delta unacceptable. Several months later, ULA/Boeing somehow heard the current Delta trajectories were to high, and within 24 hours, had the trajectories low enough to close all black zones. The NSF archives have all this mess covered in detail. I am very glad I don't work there anymore.

In 2014, the maximum "control mass" for Orion for SLS was given as 33.34 tonnes. This included the Crew Module, Service Module, Spacecraft Adapter and Launch Abort System.

The real number is probably a moving target, but remains somewhere in this ballpark.

For comparison, the heaviest mass ever lifted by an Atlas 5 was something like 7.5 tonnes for payload plus maybe 4.1 tonnes for fairing, a combined 11.3 tonnes. Black zones had nothing to do with it.

By the way, mighty Delta 4 Heavy only lifted maybe 19.8 tonnes during the EFT-1 launch including the dummy LAS and the SM panels and the adapter, and only put 11.5 to 12 tonnes into orbit. That's only halfway there ...

(To be fair, Delta 4 Heavy also orbited about 7 tonnes of propellant used for the second stage's second burn.)

This increase was clearly understood shortly after ESAS, yet it took 4 years to cancel CxP, and then they blamed the POTUS when Ares I could not get off the ground! No, it was not overweight Orion or thrust oscillation.

Sorry for overstating the mass. For the SM, its propellant could be offloaded with a LEO gas station. But right on que:

In 2014, the maximum "control mass" for Orion for SLS was given as 33.34 tonnes. This included the Crew Module, Service Module, Spacecraft Adapter and Launch Abort System.

The real number is probably a moving target, but remains somewhere in this ballpark.

For comparison, the heaviest mass ever lifted by an Atlas 5 was something like 7.5 tonnes for payload plus maybe 4.1 tonnes for fairing, a combined 11.3 tonnes. Black zones had nothing to do with it.

By the way, mighty Delta 4 Heavy only lifted maybe 19.8 tonnes during the EFT-1 launch including the dummy LAS and the SM panels and the adapter, and only put 11.5 to 12 tonnes into orbit. That's only halfway there ...

(To be fair, Delta 4 Heavy also orbited about 7 tonnes of propellant used for the second stage's second burn.)

- Ed Kyle

Thanks for pulling up the 2011 values. It became clear that Atlas Delta all had unique issues if they had to carry crew, so updates or new LVs like Vulcan would have been proposed perhaps a decade ago.

I was a NASA engineer in the middle of all this at the time it happened. Atlas trajectories had no black zones from the start. The existing Delta trajectories had black zones. I requested we ask ULA/Boeing to lower the Delta trajectories but NASA management refused to ask ULA/Boeing to do this, even though the current trajectories made the Delta unacceptable. Several months later, ULA/Boeing somehow heard the current Delta trajectories were to high, and within 24 hours, had the trajectories low enough to close all black zones. The NSF archives have all this mess covered in detail. I am very glad I don't work there anymore.

Danny,I want to thank you for taking the time and energy to speak up. Black Zones, AR&D Risk, LAS mass.... the list goes on....Wayne Hale's Stiffling Dissent says it way better than I.Thanks again.

Atlas V has an extraordinary reliable launch record. Why wasn't it upgraded to become certified for human spaceflight, especially when it was decided to cancel the STS space shuttle? It is capable to carry the CST-100 Starliner, so it is obviously intended to become human rated anyway now.

While ULA has said both Atlas V and Delta IV Heavy can safely launch humans to space (ULA paper - date unknown), when the end of the Shuttle program was coming near the end and Ares I was having development challenges, ULA proposed Delta IV Heavy to be human rated. At the time (and I can't find the slide at this moment), ULA said it would be something like $1.4B to human rate and only take a couple of years.

Quote

Why was Orion developed for a potential future much heavier launcher instead of for the already existing and proven Atlas V?

I think Michael Griffin, the NASA Administrator at that point in history, is responsible for that decision. I think it was a bad one, but no need to debate it now...